Since the scales of the offices and factories are bigger and bigger, the height thereof is higher and higher, the structures thereof are more and more peculiar and the facilities thereof are more and more complicated, the conventional fire fighting facilities may not work effectively in those situations. If the conventional monitoring system can be improved to capture and analyze images and to determine if there is flame in a building through a particular algorithm, the fire might be detected and controlled efficiently and immediately at its early stage.
The image determining method is to recognize the flame through various steps in an algorithm. The first step is to capture the images through the monitoring system. Then the motilities and the color models of the objects in the images are analyzed by the calculating processors, such as the computers and the digital signal processor (DSP). The conventional recognizing methods such as the background subtraction method, the statistical method, the temporal differencing method and the optical flow method are to separate the pixels whose pixel property difference exceeds a threshold value of the images and compare these pixels to a flame color model. If the conditions of the objects in the images meet the flame features, those objects might be identified as flame. These conventional recognizing methods use the RGB color model as a comparing basis. However, the color recognition accuracy of the RGB color model is not good enough. Therefore, the objects with a similar color to the flame are identified as having the flame properties.
Moreover, the conventional recognizing methods only use the motion detection and the color model recognition, which easily result in misrecognition and cause incorrect identification. For example, if a man dressed in red walks through the monitored area, he will be identified as a moving object with the red element of the flame features and determined as the flame, thereby triggering a false alarm.
U.S. Pat. Nos. 6,184,792 and 6,956,485 disclose some algorithms to detect early fire in a monitored area. U.S. Pat. No. 6,184,792 discloses a method and an apparatus for detecting early fire in a monitored area, which analyzes a brightness variation for video images by performing a Fast Fourier Transform (FFT) on the temporally varying pixel intensities. U.S. Pat. No. 6,956,485 discloses a flame detection algorithm to analyze a frequency variation by a filter-analyzing technology. However, the accuracy of these detecting methods is not mentioned in these patents, and other analyzing techniques, e.g. a chrominance variation analyzing, are not applied in these patents.